Adjustable tractor hood lift mechanism

ABSTRACT

A pivotally mounted hood for a tractor is disclosed wherein a gas spring, provided to offset the weight of the hood to facilitate the movement of the hood between opened and closed positions, is mounted to the chassis via a multi-position bracket having more than one hole therein for the selective connection of the gas spring. The bracket holes are arranged in a configuration defining a progressively increasing distance from the pivot connecting the hood to the chassis, thereby providing alternative mounting positions for the gas spring which have different moment arms for the application of the force exerted by the gas spring about the hood pivot. The gas spring can be remounted to a hole providing a larger moment arm relative to the hood pivot as the gas spring weakens over time due to the loss of gas therefrom, which enables the effective spring force offsetting at least a portion of the weight of the hood to remain substantially constant even though the gas spring weakens.

BACKGROUND OF THE INVENTION

This invention relates generally to off-road motor vehicles, such astractors, and more particularly, to an engine hood enclosure for thetractor engine in which the hood is rearwardly pivotable and islatchable in an intermediate opened position and a fully openedposition.

Tractors, particularly tractors used in an agricultural environment, aretypically provided with a hood enclosure that has pivotable parts toprovide access to the engine for service thereof. Generally, tractorhoods do not utilize engine hoods that pivotally move as an entire unitto provide access to the tractor engine; however, one piece hoodconfigurations can be more economically produced.

In known engine hood configurations, access for daily maintenancecomponents is attained merely by lifting or removing a side panel of theengine hood. Furthermore, raising the hood to fully expose the enginesubjects the hood to wind forces, while daily maintenance, such as oillevel checking, etc., can be accomplished without fully raising the hoodrelative to the engine. Accordingly, it would be desirable to provide arearwardly pivotable engine hood for a tractor in which the hood ispositionable in at least one intermediate position.

Economical manufacture of a one piece engine hood enclosure is adesirable goal. One piece polymer hoods have the advantage of beingmolded in an aesthetically pleasing shape; however, certainmanufacturing processes require the hood to have substantially uniformmaterial thicknesses to accomplish a high gloss exterior finish andminimize tooling costs. Accordingly, no bosses can be molded into thebody of the hood to enable the fastening of mounting components, such asthe hinge for pivotally mounting the hood to the chassis. Accordingly,it would be desirable to provide a hinge and a process for mounting thehinge to the body of the hood to facilitate the use of a one piecepolymer tractor engine hood.

Similarly, the problem of latching the engine hood in a closed positionis amplified by an engine hood configuration that does not providemounting bosses. Furthermore, the latch mechanism must be adjustable toenable the mating latch components to interengage in the prescribedmanner. The location for mounting the latch must be structurally soundand is preferably accessible from either side of the tractor. Likewise,the hinge mechanism must also be adjustable to enable a proper anddesirable mating of the engine hood to the tractor chassis or otherrelated component.

Accordingly, it would be desirable to provide a one piece engine polymerhood for tractors, while providing solutions to the problems ofpivotally mounting the hood, latching the hood and restricting thepivotal movement thereof.

The pivotal raising of a one piece hood requires the assistance of aspring assist mechanism to counterbalance the weight of the hood andfacilitate the manual lifting of the hood. Gas springs can be utilizedto offset the weight of the hood; however, gas springs often losegradually the nitrogen gas from inside the spring. As a result, theforce exerted by the spring lessens and causes the raising of the hoodto become more difficult. Accordingly, it would be desirable to providea mounting mechanism that could be adjustable to accommodate the changesin spring force and extend the operative life of the gas spring.

SUMMARY OF THE INVENTION

It is an object of this invention to overcome the aforementioneddisadvantages of the prior art by providing a one piece polymer hood toenclose the engine compartment of a tractor.

It is another object of this invention to provide a hinge mechanism, alatching apparatus and a position control mechanism for a one piecepolymer engine hood manufactured without mounting bosses.

It is still another object of this invention to provide a mechanism tolimit the extent of pivotal movement of the engine hood to provide atleast two opened positions to expose the engine to various degrees ofexposure.

It is a feature of this invention that the mechanism for limiting thepivotal movement of the engine hood includes a slide mechanism havingfirst and second slotted openings interconnected by a passageway toprovide an intermediate opened position offering only limited exposureto the tractor engine.

It is an advantage of this invention that the mechanism for limiting thepivotal movement of the engine hood requires manual manipulation to movethe slide mechanism to allow the further movement of the engine hood tothe fully opened position.

It is another advantage of this invention that the slide mechanismallows sufficient pivotal movement of the engine hood to gain access toall of the maintenance items requiring daily service, yet minimizes theexposure of the engine hood to wind forces by keeping the engine hood ata lower profile.

It is still another object of this invention to provide a mechanism forlimiting the pivotal movement of a one piece polymer hood for anagricultural tractor which is durable in construction, inexpensivemanufacture, carefree of maintenance, facile in assemblage, and simpleand effective in use.

It is yet another object of this invention to provide a latchingmechanism that can be operable with a one piece polymer tractor hood.

It is still another feature of this invention that the latchingmechanism is adjustable to enable the mating latch components tointerengage in a prescribed manner.

It is still another advantage of this invention that the latchingmechanism is mounted on a one piece polymer tractor hood in a manner tobe structurally sound and accessible from either side of the tractor.

It is a further object of this invention to provide an adjustablelatching mechanism for an agricultural tractor which is durable inconstruction, inexpensive manufacture, carefree of maintenance, facilein assemblage, and simple and effective in use.

It is yet another object of this invention that the hinge mechanism canbe integrated into the one piece tractor hood design in a strong andcost effective manner.

It is yet another advantage of this invention that the hinge support ismovable to provide adjustment of the tractor hood in a side-to-sidemanner.

It is yet another feature of this invention that the hinge supportincludes a portion pivotable about a center pin and secured by a pair ofbolts to provide a side-to-side adjustment of the one piece hood member.

It is a further feature of this invention that the hinge supportincludes an lower portion fixed to the block of the tractor engine andan upper portion pivotally supported on the lower portion to provideside-to-side adjustment.

It is a further object of this invention to provide a mechanism forpivotally supporting a one piece tractor hood from a tractor chassis toprovide side-to-side adjustment thereof, which is durable inconstruction, inexpensive manufacture, carefree of maintenance, facilein assemblage, and simple and effective in use.

It is still a further object of this invention to provide a mountingmechanism for gas springs counterbalancing the weight of the tractorhood enclosure that is adjustable to increase the mechanical advantageof the gas spring as the spring force weakens over time.

It is still a further feature of this invention that the mountingbracket is provided with a plurality of mounting positions that vary themoment arm through which the spring force is exerted to offset theweight of the hood.

It is a further advantage of this invention that the operative life ofthe gas spring as part of a hood lift mechanism is increased.

It is still a further advantage of this invention that the gas springcan be re-mounted in an alternative mounting position to maintain asubstantially constant counterbalancing force as the gas spring weakensover time.

It is yet another feature of this invention that the re-mounting of thegas spring to alternate mounting positions can be accomplished withoutproviding additional parts.

It is yet a further object of this invention to provide an adjustablemounting mechanism for the gas spring forming part of a hood liftmechanism which is durable in construction, inexpensive manufacture,carefree of maintenance, facile in assemblage, and simple and effectivein use.

These and other objects, features, and advantages are accomplishedaccording to the instant invention by providing pivotally mounted hoodfor a tractor wherein a gas spring, provided to offset the weight of thehood to facilitate the movement of the hood between opened and closedpositions, is mounted to the chassis via a multi-position bracket havingmore than one hole therein for the selective connection of the gasspring. The bracket holes are arranged in a configuration defining aprogressively increasing distance from the pivot connecting the hood tothe chassis, thereby providing alternative mounting positions for thegas spring which have different moment arms for the application of theforce exerted by the gas spring about the hood pivot. The gas spring canbe remounted to a hole providing a larger moment arm relative to thehood pivot as the gas spring weakens over time due to the loss of gastherefrom, which enables the effective spring force offsetting at leasta portion of the weight of the hood to remain substantially constanteven though the gas spring weakens.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of this invention will be apparent upon consideration ofthe following detailed disclosure of the invention, especially whentaken in conjunction with the accompanying drawings wherein:

FIG. 1 is a side elevational view of a tractor incorporating theprinciples of the instant invention;

FIG. 2 is an enlarged top plan view of the hood enclosure shown in FIG.1, the engine and various mounting components for the hood being shownin phantom;

FIG. 3 is an exploded perspective view of the hood enclosure shown inFIG. 2, the hood and components bonded thereto being separated from thechassis mounting subframe and hinge support;

FIG. 4 is a simplified top plan view of the hood enclosure similar tothat of FIG. 2, the side-to-side adjustment movement of the hood fromthe hinge support being shown in phantom;

FIG. 5 is a cross-sectional view taken along lines 5--5 of FIG. 4 todepict the details of the hinge support, the structure to which thehinge support is mounted being shown in phantom;

FIG. 6 is an enlarged detail view of the slotted bolt connectionallowing a pivotal movement of the hinge support for side-to-sideadjustment of the hood, as shown in phantom;

FIG. 7 is a side elevational view of the hood enclosure shown in FIG. 2,most of the side portion of the hood being broken away to better showthe various mounting components and chassis subframe;

FIG. 8 is a schematic side elevational view of the hood shown in FIG. 7with the hood raised to an intermediate opened position;

FIG. 9 is a schematic side elevational view of the hood similar to thatshown in FIG. 8, but with the hood raised to a fully opened position;

FIG. 10 is a schematic side elevation view of the hood enclosure in theclosed position and depicting the alternate mounting positions of thegas spring counterbalancing the weight of the hood and the resultantchanges in the moment arm through which the spring force is applied; and

FIG. 11 is a schematic side elevation view of the hood enclosure similarto that of FIG. 10, except with the hood moved to the fully openedposition and depicting the alternate mounting positions of the gasspring counterbalancing the weight of the hood and the resultant changesin the moment arm through which the spring force is applied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings and, particularly, to FIGS. 1-3, arepresentative view of an agricultural tractor incorporating theprinciples of the instant invention can best be seen. Left and rightreferences are used as a matter of convenience and are determined bystanding at the rear of the tractor and facing the forward end in thenormal direction of travel. The tractor chassis 10 houses a conventionalengine 12 serving to provide operational power for the tractor T and anoperator's cab 13 positioned in an elevated location. The operator's cab13 includes a steering wheel 14, positioned forwardly of theconventional operator's seat (not shown), to operate the steering of thefront wheels 11 in a known manner. The chassis 10 is supported above theground G in a conventional manner by forward steerable wheels 11 andrearward drive wheels 16 rotatably mounted in a customary transverselyspaced orientation.

The hood 20 is mounted on the chassis 10 forwardly of the operator's cab13 to enclose the engine 12. The hood 20 is pivotally mounted by a hingemechanism 30 defining a generally horizontal, transverse hinge axis 39positioned next to the operator's cab 13 to enable the hood to moveupward and rearwardly toward the operator's cab 13. Gas springs 24detachably connected to mounting brackets 25 affixed to the chassissubframe 15 interconnect the chassis 10 and the hood 20 tocounterbalance a major portion of the weight of the hood to facilitatethe manual lifting of the hood 20 in a manner described in greaterdetail below.

A latching mechanism 40 retains the hood 20 in its closed positioncompletely enclosing the engine 12. The chassis subframe 15 is supportedon the engine block 12a, which in turn is supported from the chassis 10,to provide support for the various mounting components as described ingreater detail below. A slide mechanism 50 limits the opening of thehood from the closed position and defines an intermediate openedposition from which most of the routine servicing of the engine 12 canbe accomplished, as will also be described in greater detail below.

As best seen in FIGS. 3-7, the hinge mechanism 30 includes a hingesupport 32 having a lower portion 33 detachably affixed to the engineblock 12a and to the chassis subframe member 15 by fasteners. The hingesupport 32 also has an upper portion 34 pivotally attached to the lowerportion 33 by a generally vertically extending central pivot pin 35 andby a pair of opposing lateral fasteners 36 extending through respectiveslotted openings 37 in the lower portion 33 to clamp the upper and lowerportions 33, 34 together, yet provide a limited range of relativepivotal movement therebetween about the central pivot pin 35. The upperportion 34 also carries a pair of laterally disposed hinge pins 38 toprovide a generally horizontally disposed hinge axis 39 for the onepiece hood 20.

The pivotal movement of the upper portion 34 of the hinge support 32relative to the lower portion 33 provides a side-to-side adjustment ofthe hood 20, as depicted in phantom in FIG. 4, to permit the orientationof the hood 20 to be matched to the chassis 10 for proper enclosure ofthe engine 12. By loosening the lateral fasteners 36, the upper portion34 can be pivoted about the central pivot pin 35, which in turn rotatesthe hinge axis 39, to which the hood 20 is attached, about the centralpivot pin 35. The slotted openings 37 provide a limited range of pivotalmovement of the upper portion 34. A re-tightening of the lateralfasteners 36 locks the upper portion 34 against the lower portion 33 tofix the orientation of the hood 20 relative to the chassis 10.

The hood 20 has a contoured surface to provide a pleasing aestheticappearance. The top portion 27 of the hood 20 is manufactured preferablyfrom a polymer such as fiberglass reinforced polyester with directedfiber preform by a process called liquid composite molding, whichprovides a high gloss finish, but does not permit the incorporation ofmounting bosses. The thickness of the material is approximately 4millimeters. The side panels 28 are also preferably manufactured fromfiberglass reinforced polyester by a manufacturing process called sheetmolding compound, which allow for the incorporation of mounting bosses.The side panels 28 are bonded to the top portion 27 by high tech, heatcured adhesives. As a result, the hood 20 can be pre-formed from polymermaterial with a relatively uniform thickness to provide a low cost hoodwith satisfactory strength characteristics and a high gloss exteriorfinish.

A hinge casting 31, preferably constructed of aluminum so that thethermal expansion of the hinge casting 31 is similar to that of thepolymer hood 20, is formed with the same contoured shape as the interiorsurface of the top portion 27 of the hood 20 to which the hinge casting31 is to be attached. The hinge casting 31 is bonded to the underside ofthe hood 20 with the same heat cured adhesives to form a permanent bondwith the hood 20. The hinge casting 31 is then connected to the hingesupport 32 to pivotally mount the hood 20 to the chassis 10 for movementabout the rearwardly located hinge axis 39.

Referring to FIGS. 3, 4 and 7, one skilled in the art will see that thelatching mechanism 40 includes a centrally positioned latch pin 42attached to a central hood support 43 bonded to the interior surface ofthe top portion 27 of the hood 20 in substantially the same manner asthe hinge casting 31. The releasable clasp 45 is supported from thechassis subframe 15 at a position to engage with the latch pin 42 whenthe hood 20 is moved to a closed position. A latch release linkage 46includes a pivoted handle 47 positioned for convenient access by theoperator and a connecting link 48 interconnecting the handle 47 and thereleasable clasp 45 to transfer the pivoted motion of the handle 47 tothe clasp 45 to effect actuation thereof in a conventional manner. Oneskilled in the art will recognize that the latch release linkage canalso be formed as an equivalent cable release.

Referring now to the views of FIGS. 3, 4 and 7-11, the mechanism 24, 50for controlling the pivotal movement of the hood 20 can best be seen.The raising of the hood 20 is assisted by gas springs 24 positioned onopposing sides of the hood 20. The nitrogen gas filled springs 24provide a lifting force to offset the weight of a major portion of thehood 20 and attached components, such as the hinge casting 31 and thecentral hood support 43. As a result, the hood 20 is easier to liftmanually when the latch pin 42 is released from the clasp 45. Since thenitrogen gas tends to escape from the springs 24 over a period of time,thereby causing the gas springs to weaken and lose spring force, it isundesirable that the overall counterbalance effect of the gas springs belost.

Accordingly, the gas springs 24 are oriented between the central hoodsupport 43 and the mounting brackets 25 affixed to the chassis subframe15. The mounting brackets 25 are formed with at least two mounting holes26 that are generally aligned with the hinge axis 39 such that mountinghole 26a is closer to the hinge axis 39 than mounting hole 26b. Thelifting force of the gas springs 24 about the hinge axis 39 is a productof the spring force of the gas springs multiplied by the linear distance(M1, as depicted in FIGS. 10 and 11) between the mounting hole 26 towhich the gas springs 24 are connected and the hinge axis 39.

By re-mounting the gas springs 24 at the alternate mounting hole 26b,the distance M2 between the mounting hole 26b and the hinge axis 39 isgreater than the distance M1. As a result, the lifting force of the gassprings 24 can be maintained substantially constant as the spring forcelessens by increasing the moment arm M1, M2 through which the springforce acts. One skilled in the art will realize that more than twomounting holes 26 can be provided to give yet a greater range ofadjustment of the lifting force of the gas springs 24.

Because of the overall size of the hood 20, the amount of pivotalmovement of the hood 20 about the hinge axis 39 required to fully exposethe engine 12 to access by the operator is quite substantial. While afully opened hood 20 is necessary for some maintenance or repair of theengine 12, normal daily maintenance generally requires only a partialopening of the hood 20 to an intermediate opened position. Pivotalmovement of the hood 20 to an intermediate opened position alsominimizes the exposure of the hood 20 to the wind or other externalforces.

A slide mechanism 50 is provided to limit the movement of the hood 20 toan intermediate opened position unless manually manipulated to allowfurther pivotal movement of the hood 20 to the fully opened position.The slide mechanism 50 includes a slide pin 52 mounted to the chassissubframe 15 and extending generally horizontally outwardly therefrom. Aslide member 55 is pivotally connected to the central hood support 43 soas to be movable with the hood 20 about the hinge axis 39. The slidemember 55 has a bayonet slot 56 formed therein from a first opening 57and a generally parallel second opening 58 interconnected by apassageway 59 extending perpendicularly thereto to form a continuous,two-part bayonet slot 56. The slide pin 52 is positioned within thebayonet slot 56 for slidable movement therein while the hood 20pivotally moves about the hinge axis 39.

Due to the configuration of the bayonet slot 56, the slide pin 52 stayswithin the first opening 57 when the hood is moving between the closedposition and the intermediate opened position, as depicted in FIG. 8,the force of gravity keeping the slide member 55 resting against theslide pin 52 so that the slide pin 52 bottoms out against the end of thefirst opening when the hood reaches the intermediate opened position. Topermit the hood to open beyond the intermediate opened position to thefully opened position, the slide member 55 must be manually lifted toallow the slide pin 52 to pass along the passageway 59 interconnectingthe first and second openings 57, 58 and enter the second opening 58.The slide pin 52 can then move within the second opening 58 as the hood20 pivotally moves to the fully opened position. The distal end of thesecond opening 58 is enlarged to allow the slide member 55 to fall bygravity when the hood 20 reaches the fully opened position and therebyrestrain the hood 20 in the fully opened position until manually movedto allow the slide pin 52 to move within the second opening 58.

A hood 20 constructed as described above can be manufactured withrelatively low cost tooling in a cost effective manner. The hood issupported on three points, the two laterally spaced rearward hinge pins38 and the latch pin 42, which simplifies adjustment and reducescomplexity. The slide mechanism 50 controls the opening height of thehood 20 and also serves as a safety catch in the event of a failure of agas spring 24 if the hood 20 is moved beyond the intermediate openedposition. The hinge components 31, 32 provide accurate adjustment of thehood 20 relative to the chassis 10 and can be integrated into the hoodstructure to provide strength and cost effectiveness.

It will be understood that changes in the details, materials, steps andarrangements of parts which have been described and illustrated toexplain the nature of the invention will occur to and may be made bythose skilled in the art upon a reading of this disclosure within theprinciples and scope of the invention. The foregoing descriptionillustrates the preferred embodiment of the invention; however,concepts, as based upon the description, may be employed in otherembodiments without departing from the scope of the invention.Accordingly, the following claims are intended to protect the inventionbroadly as well as in the specific form shown.

Having thus described the invention, what is claimed is:
 1. In a tractor having a wheeled chassis adapted for movement over the ground; an engine supported on said chassis to provide operative power for said tractor; a hood pivotally supported from said chassis for movement about a pivot between a closed position and an opened position; and a spring operatively interconnecting said hood and said chassis to offset a portion of the weight of said hood to facilitate a manual movement of said hood between said opened and closed positions; the improvement comprising:said spring being mounted on said chassis by a multi-position bracket providing a selectively variable moment arm for the application of the force exerted by said spring about said pivot.
 2. The tractor of claim 1 wherein said spring is a gas spring and said multi-position bracket is provided with a plurality of holes therein for the connection of said gas spring thereto.
 3. The tractor of claim 2 wherein said holes are oriented in a configuration having a progressively increasing distance from said pivot.
 4. A tractor comprising:a chassis mobilely supported over the ground by ground engaging wheels; an engine mounted on said chassis to provide a source of operative power for said tractor; a hood pivotally connected to said chassis for movement relative thereto about a hood pivot between a closed position, in which said hood covers encloses said engine, and an opened position, in which said engine is exposes for convenient access thereto; a spring interconnecting said chassis and said hood and being operable to offset at least a portion of the weight of said hood to facilitate the movement thereof between said closed and opened positions; and a multi-position bracket affixed to said chassis for the connection of said spring, said multi-position bracket having at least two holes therein for the selective alternative connection of said spring to provide different selectable moment arms for the application of the force exerted by said spring about said hood pivot.
 5. The tractor of claim 4 wherein said spring is a gas spring, said holes being oriented within said bracket in a configuration defining a progressively increasing distance from said hood pivot, said gas spring being detachably connectable to a selected one of said holes to increase the moment arm of said spring force as said gas spring loses gas therefrom, thereby maintaining a substantially uniform effective spring force as applied to said hood, even though said gas spring weakens by the loss of gas therefrom. 